Project Summary/Abstract This proposal addresses the growing clinical need for non-invasive diagnostic tools that can efficiently evaluate middle ear diseases. Physical Sciences Inc. (PSI), in collaboration with the Massachusetts Eye and Ear Infirmary (MEEI), proposes to develop a clinically viable multimodal otoendoscopic imaging instrument that can analyze middle ear morphology, function, and biochemical changes in vivo in real-time. This will be possible by combining phase-sensitive optical coherence tomography (PsOCT) and Raman spectroscopy (RS) with a conventional video otoendoscopy (VO). Although this system can be applicable to various middle ear pathologies including otitis media, cholesteatoma, myringosclerosis and adenoma, in Phase I we will focus on otitis media (OM), a complex infection and inflammatory disease with the highest prevalence in the middle ear. During Phase I, PSI and MEEI will demonstrate the diagnostic capability of the multimodal imaging system. A prototype of the multimodal PsOCT/RS otoendoscopic system will be optimized on human cadaveric temporal bones, and then its capability for OM diagnosis will be evaluated on human patients. Based on the Phase I results and conclusions, a robust otoendoscopic system with improved performance and suitable size and design for clinical use in various middle ear pathologies will be proposed to be developed and validated on human patients in Phase II.